1. Field of the Invention
The present invention relates to a method and apparatus for performing intra prediction mode decoding on digital video data that has been encoded using an intra prediction mode. The present invention also relates to a method and apparatus for signaling the proper intra prediction mode to a decoding unit.
2. Discussion of the Related Art
Generally, there are two methods for accomplishing video compression encoding in order to eliminate temporal and spatial redundancy. Eliminating temporal and spatial redundancy is an important requirement to increase a compression ratio of a video signal in order to decrease an overall size of a video data transmission.
An inter prediction encoding method is able to predict a current video data block based on similar regions found on a previously encoded picture that temporally precedes a current picture that includes the current video data block. And an intra prediction encoding method is able to predict a current video data block based on previously encoded blocks that are adjacent to the current video data block and within a same picture. The inter prediction method is referred to as a temporal prediction method, and the intra prediction method is referred to as a spatial prediction method.
Video data comprised of inter predicted and intra predicted video data pictures are transmitted to a receiver and then decoded to reproduce the video data. A decoding unit must perform the proper prediction mode processing in order to reconstruct the received video data.
Pertaining to the intra prediction method of encoding, there exists various modes for accomplishing the spatial prediction that defines the intra prediction method. And within both the inter and intra prediction methods, the prediction for a luminance (luma) sample is handled separately from a prediction of a chrominance (chroma) sample. Luminance can be defined as the brightness of an image, and chrominance can be defined as a representation of color difference within an image. Although both luma and chroma are important components in any picture image, due to the human visual system being more sensitive to variences in luminance as compared to variences in chrominance, prediction modes have generally been more concerned with luma prediction modes compared to chroma prediction modes.
Accordingly, none of the currently recognized chroma prediction modes contemplate reconstructing a chroma sample by utilizing a linear combination of interpolated luma samples. By taking advantage of the interpolation of luma samples, where the luma samples have been previously reconstructed, a new mode for efficiently predicting the chroma sample can be achieved.
There also exists a need to conserve a number of codeword bits when transmitting binary codewords related to information transmitted along with video data as part of the overall video data signal. When transmitting large amounts of video data, it becomes even more important to conserve the number of codeword bits that are transmitted along with the video data in order to conserve the number of overall bits being transmitted. This allows for a more efficient compression of the video data signal as a whole.